Date   

Re: sighting: Beaverton-built 5110 Mod 709V for Bently Nevada

 

On Mon, Feb 8, 2021 at 08:17 AM, Paul McClay wrote:

Is "L vs H" correct for the 5B10N switch mod? That seems odd when the function I assume, Left vertical amp vs _not_ Horizontal sweep.
Yes off course it should be L vs R

Are "Description", "Bandwidth" & "Calibration" same-level headings? Or Description & Calibration with Bandwidth under Description? Or otherwise?
I'm not sure understand the question correctly .... but here is what is said about Calibration:

//
5A19 MOD 709V CALIBRATION

Calibrate the same as standard with the following additions regarding offset.

Check OFFSET for ±15 volts in all Volts/Div positions.

1. Ground amplifier inputs and set display in center screen with
OFFSET in OFF position, and Volts/Div in .5 Volt/Div position.

2.Turn OFFSET to ON position and position trace 1 cm above center
screen. Plus .5 volts OFFSET.

3. Change Volts/Div to .2 position. Trace should now be 2-1/2 cm
above center screen. If trace shifts toward center screen instead,
offset strap on board is in wrong position. Strap should be in
position #2.

5B10 MOD 709V CALIBRATION

Calibrate this instrument the same as standard except as follows:

1. Variable TIME/DIV is deleted - no checks required.

2. Fully ccw position of TIME/DIV switch used to be EXT INPUT .5 VOLTS
PER DIV. This feature is deleted and is now marked L vs R (left vertical versus
right vertical). In this position check to see that -30 volts is present at
contact A-12 of interface connector. Voltage should not appear at A-12 in any
other position of timing switch.
//

/Håkan


2465B CH1,2 compression

Jean-Paul
 

Rebonjour a tous:
Same low SN B062 2465B
has extrême CH1,2 compression on lower part of display.

CH 3, 4 are perfect and normal.

Photo Album: 2465B CH1,2 compression

Taken with 100 kHz triangle on CH 1 and CH2,
position upper nearly linear position lower screen, extreme compression and non linearity.
Transient response is also severely affected as position of traces is moved.

1/ all PSU voltages normal,

2/ using substitute A5 so no CAL data is valid.

3/ Is there an adjustment or bias eg on U400 channel sw ?

4/ Pulled U400, cleaned the hybrid contacts, no change

is there a place to test signals into U400 from CH 1,2 preamp U100, U200?

Assume U400 155-0236-00 is bad and replace (VERY costly!)

Many thanks

Jon


2465B CTT options board faults

Jean-Paul
 

Bonjour a tous:
Working on SN B062 2465B, GPIB and CTT/WR options.
Faults in CTT option. Affects triggering.

All cables are correctly attached to options board,
A5 board is not at fault, SMD leaks and damages repaired, swapping other good A5 does not remove fault and removing options board clears the fault.

Turn on test Test 05, Fail 42 LINE TRIG signal to the Trigger hybrid.
Line sig is OK and trig hybrid U500 can be replaced with no changes.

CTT test errors:
81 fail 03
82 fail 3F
83 fail 30
84 fail 40
85 fail 03
86 fail 02
87 fail 58

The 5 pages flow charts of option serv man do not point to a good procedure.
I suspect that the EEPROM on options board U5930 27515 may have bad data.

Note: NO TV or HDTV options, no REF FREQ ext in, only CTT/WR.
GPIB on separate board seems OK and no effect to insert or remove GPIB.

Any experience or assistance on CTT board faults greatly appreciated.

Mille mercis!

Jon


Re: Spectrum analyzer Tektronix 7L13 on mainframe Tektronix 7603

Attilio
 

Thanks a lot Ed.
I try in the day.

--Cheers
Attilio


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Tom Lee
 

Great background story, Stephan. Always glad to have another Tek fan join in the fun!

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 2/8/2021 01:58, Stephan Lonis wrote:
Yep, if I would have just checked every tantalum first instead of looking through the schematic to figure out what the 15 volt supply was connected to it probably would have been quicker. I think it was c976 or c972 something like that. I did check all tantalums after I found that one though and the rest checked out fine. I had time to spare this weekend and spent a good chunk of time on it. This is the second tektronix scope I own my first one was the 2465a. Just got a siglent dso 1104x-e, and have another pc digilent analog discovery 2. I seem to have a special love for the tektronix scopes though. They are fascinating to me and I really like them. This is the first mainframe I have owned. Picked it up at a ham radio auction for $50 I think a couple years ago. It sat for a while after I plugged it in and heard what sounded to me like a power supply problem. Fast forward two years after sitting and I decided it was finally time to repair it. Replaced the tantalums in the power supply and after that the plugins it came with worked with the exception of one which is a 7a24 which ch1 is not working. Purchased a refurb 7a19 in the meantime and have a 7a26 in the other vertical. Have a 7b53a and 7b85 also both working. I picked up this 7b92a on eBay with service manual and an operators manual, original for a good price. It said working pull but showed up DOA. Rather than go through the trouble of returning it I thought I would try and repair it as I did get it for a really good price that included the original manuals. I’ve been around electronics all my life. My Father is a service technician and repairs things daily. In fact most of my acquired equipment sits in his shop and I keep it there so he can use it and I just go over to the shop when I want to use it. This type of scope has been a bit new to us but the basic principles of electronic components are the same. Well that was a bit long but since I never really introduced myself to the group there is a little bit of background blended in.




Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Stephan Lonis
 

Yep, if I would have just checked every tantalum first instead of looking through the schematic to figure out what the 15 volt supply was connected to it probably would have been quicker. I think it was c976 or c972 something like that. I did check all tantalums after I found that one though and the rest checked out fine. I had time to spare this weekend and spent a good chunk of time on it. This is the second tektronix scope I own my first one was the 2465a. Just got a siglent dso 1104x-e, and have another pc digilent analog discovery 2. I seem to have a special love for the tektronix scopes though. They are fascinating to me and I really like them. This is the first mainframe I have owned. Picked it up at a ham radio auction for $50 I think a couple years ago. It sat for a while after I plugged it in and heard what sounded to me like a power supply problem. Fast forward two years after sitting and I decided it was finally time to repair it. Replaced the tantalums in the power supply and after that the plugins it came with worked with the exception of one which is a 7a24 which ch1 is not working. Purchased a refurb 7a19 in the meantime and have a 7a26 in the other vertical. Have a 7b53a and 7b85 also both working. I picked up this 7b92a on eBay with service manual and an operators manual, original for a good price. It said working pull but showed up DOA. Rather than go through the trouble of returning it I thought I would try and repair it as I did get it for a really good price that included the original manuals. I’ve been around electronics all my life. My Father is a service technician and repairs things daily. In fact most of my acquired equipment sits in his shop and I keep it there so he can use it and I just go over to the shop when I want to use it. This type of scope has been a bit new to us but the basic principles of electronic components are the same. Well that was a bit long but since I never really introduced myself to the group there is a little bit of background blended in.


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Stephan Lonis
 

It wasn’t exactly easy to replace but got it done. Had to place my
soldering iron underneath rotary switch towards the back of the 7b92a at
which point I was wishing I had more then two hands and melt the solder to
pull out the bad cap. It was a cap soldered alongside one of the coils
coming into 15 volts. I replaced a few other caps while I was inside the
unit with some higher temp, higher quality caps. In all probably 5
capacitors but the main culprit was that tantalum on the 15 volt rail.
After that plugged the plug-in back in and it was working after that.


Re: Teitronix 492a : TUNING FAILURE - 1st LO

John Miles
 

Until you fix the first LO unlock error, it is normal for it to be sluggish. The CPU is wasting time trying to lock a loop that won't lock.

Later versions of the 49x analyzers had a menu option to disable the tuning routine, so the CPU would run normally in the presence of an error, but I don't believe there was a way to do that in the 492.

-- john, KE5FX

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Bent Andersen
Sent: Sunday, February 07, 2021 10:30 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Teitronix 492a : TUNING FAILURE - 1st LO

Hi Ulf

tnx fer reply...but I think it is the cpu board there is defect.... I made a new
video,,,https://photos.app.goo.gl/HhBVr7KVjceQgpqeA

Ben



Re: Extracting a buggered knob grubscrew

Paul McClay
 

On Tue, Feb 2, 2021 at 11:21 PM, snapdiode wrote:


Here's a key I found in my toolbox, surely the only reason I bought it was to
wrestle with a Tek set screw at some point.

https://www.ebay.ca/itm/0-9-3mm-Hex-Screwdriver-Kit-For-RC-Helicopter-Drone-Aircraft-Model-Repair-Tools/132854596436
1.27 & 1.3 mm drivers... if they actually differ by 0.03 mm that would suggest goodness indeed.


Re: sighting: Beaverton-built 5110 Mod 709V for Bently Nevada

Paul McClay
 

Thanks again for the add'l info - and for taking the time to transcribe it. I've added it to TekWiki.

Interesting that the timebase mode switch apparently differs between the doc & photographed units.

A couple more questions:

Is "L vs H" correct for the 5B10N switch mod? That seems odd when the function is, I assume, Left vertical amp vs _not_ Horizontal sweep.

Are "Description", "Bandwidth" & "Calibration" same-level headings? Or Description & Calibration with Bandwidth under Description? Or otherwise?

Thanks again for help with the real reference material.


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Tom Lee
 

Glad that it was as simple as expected. That's a nice timebase, and I'm sure you'll enjoy using it.

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 2/7/2021 22:28, Stephan Lonis wrote:
Tracked it down to a bad tantalum on the 15 volt supply on the main interface board inside the 7b92a. Replaced the bad tantalum and now everything is working as it should.




Re: Teitronix 492a : TUNING FAILURE - 1st LO

Bent Andersen
 

Hi Ulf

tnx fer reply...but I think it is the cpu board there is defect.... I made a new video,,,https://photos.app.goo.gl/HhBVr7KVjceQgpqeA

Ben


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Stephan Lonis
 

Tracked it down to a bad tantalum on the 15 volt supply on the main interface board inside the 7b92a. Replaced the bad tantalum and now everything is working as it should.


Re: Teitronix 492a : TUNING FAILURE - 1st LO

Bent Andersen
 

Hi Miguel

I have made a new video, and I think it is the CPU board there is defect... if you look at the video, you can see that the keypad is working slowly, and you can move the knops and 1-2sec later it move....

https://photos.app.goo.gl/HhBVr7KVjceQgpqeA

so i will try to look for bad component's maybe try the "cold-spray" !!!

Ben


Re: Extracting a buggered knob grubscrew

Frank DuVal
 

Kroil is excellent.

But also try 50/50 mix of ATF and Acetone. That's any automatic transmission fluid and Acetone.

Of course if you have to buy a quart of fluid and a quart of Acetone, one can of Kroil may be cheaper if available locally.

Frank DuVal

On 2/2/2021 4:44 PM, JJ wrote:
I used a drop of Kroil on a 7000 plugin knob set screw when it was frozen.
That stuff never lets me down. Of course, you need to use it before you
strip the screw head! And, you need to be patient - like a few drops over
an 8 hour period. Be careful that you don't get the stuff on the face of a
Tek instrument - it will likely take the print off. But, just about
anything other than a lightly water damped cloth will take the print off a
Tek instrument.

JJ


Re: 2465B CRT board values

Hirofumi Momose
 

Hello Chuck, Jon

Chuck wrote:
I haven't found a 2465B that has its best focus at 12:00
Oh.. My unit is just 'normal'. Understand.

Jon wrote:
"If it ain't broke don't fix it"
"leave well enough alone"
Now works. Best focus point of trace/readout is a bit different.
But no problem to read.
Yes ,no more tune and leave it.

Thank you.
Hirofumi JJ2PNX


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

Ed Breya
 

Yes Reinhard, if the bad caps aren't among the "easy" (to access) ones, you have to dig deeper, and possibly disassemble some things to get to them. Then having an idea of which supply and which sub-assembly is involved definitely helps to narrow it down, especially for the bigger, more complicated plug-ins. Murphy's Law would dictate that the bad caps will be the most inaccessible, which happens sometimes, but on single-wide ones, especially verticals, there aren't all that many Ta caps to begin with, and not many that are too hard to access. Horizontals tend to have more layers of stuff, but often can be quick-tested with simple disassembly if needed, or accessing from the back (board layout info from the manual helps here too) or other accessible points on the same nodes.

The quick test can actually be even quicker than I described, in cases where you know that all the caps are simply bypassing to ground, and not between supplies. I think this is almost always the case with 7K plug-ins. Instead of probing caps with two leads for the ohmmeter, one lead can be grounded, and the other one used to make two measurements - one from each cap lead. One will show ground continuity, and the other should be a reasonably high resistance, unless the cap or the line it's on is dumped to ground. You don't care which is which, only that one lead is ground, and the other far from it.

Ed


Re: TEK 465 S/N>25000 Power Supply Issue

Ozan
 

Hi Craig,
These voltages look OK for the given pin 7 voltage and the current through R1549 is very small at 7.2mA. All of this current has to come from U1524B to sink 22V supply. My best guess is collector supply of Q1544/Q1546 is not there. There is no value marked but should be above 17V.

Ozan


Oran,

Thanks for starting this discussion.
Here are the values you were asking about.
When everything is connected, what voltages do you see:
At 15V TP. 1.675vdc
At the emitter of Q1546. 1.683vdc
At the base of Q1546. 2.223vdc
pin 7 of U1524B 2.988vdc
base of Q1548B. 2.084vdc
Voltage across R1549 (this tells us how much current is pulled from Q1546).
0.008vdc

We are looking for a possible high current out of U1524B pin 7 (~ 10mA).

Craig


Re: Tektronix 7b92a shuts down crt & graticule illumination on 7904 mainframe

n49ex
 

I agree in general, except in this case, given how densely packed the 7B92A is, it may be easier to know up front which power supply is the offender. And having to trace that power net through the unit using the schematic is a good learning experience anyway👿. And I would not be surprised if it is the entry filter cap, close to the connector.

Reinhard


Re: TEK 465 S/N>25000 Power Supply Issue

Craig Cramb
 

Oran,

Thanks for starting this discussion.
Here are the values you were asking about.
When everything is connected, what voltages do you see:
At 15V TP. 1.675vdc
At the emitter of Q1546. 1.683vdc
At the base of Q1546. 2.223vdc
pin 7 of U1524B 2.988vdc
base of Q1548B. 2.084vdc
Voltage across R1549 (this tells us how much current is pulled from Q1546). 0.008vdc

We are looking for a possible high current out of U1524B pin 7 (~ 10mA).

Craig

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